Centrifugal casting molds



4 Sheets-Sheet 1 Filed Aug. 12, 1952 V/TV J. SEEBA El AL July 3, 1956 edAug. 12, 1952 Inventors: 8A, ER EIEFAHGP July 3, 1956 CENTRIFUGALCASTING MOLDS g 4 Inventory? J'oHAnrI SEEBAI PETER BIEHVYG- A'Ho ALFRED.Srmoms J. SEEBA ETAL 2,752,651 I July 3, 1956 J. SEEBA EIAL CENTRIFUGALCASTING MOLDS 4 Sheets-Sheet 4 Filed Aug. 12, 1952 0am SEE MP ALFRED BY.

2,752,651 CENTRIFUGAL CASTING MOLDS Johann Seeba,

Gelsenkirchen, Gelseukirchen, many Application August 12, 1952, SerialNo. 303,882 Claims priority, application Germany August 13, 1951 11Claims. (Cl. 22-1135) Peter Biefang, and Alfred imonis, Germany,assignors to Eisenwerke Aktiengesellschaft, Gelsenkirchen, Ger= stresseson the mold wal However, the above mentioned grooves have seriousdisadvantages. Thus, when the molded article is re- Moreover, with moldshaving an inner surface provided with axially and circnmferentiallyextending grooves, the axially extending grooves gradually become widerand the circumferentially extending grooves gradually close shape for along period of time and will not easily become closed up.

Yet another object of the present invention is to pro a mold grooveswhich will the inner mold surface.

silicon powder.

A still further object of the present invention is to provide on theinner surface of a centrifugal mold a patto an axis normal 2 tern ofgrooves which form between themselves areas capable of becomingautomatically grouped in different ways to best suit the particularmolding conditions.

An additional object of the present invention is to provide a processfor easily and quickly forming grooves of the above type on the interiorof the mold.

A still additional object of the present invention is to prevent theformation of cracks at those parts of a mold which are subjected torelatively high stresses.

to the longitudinal axis, these grooves preferably making an angle ofbetween 40 and 50 with these axes. In a preferred form grooves arearranged in a honeycomb pattern.

The novel features which are considered as characteristic for theinvention are set forth in particular in the appended claims. Theinvention itself, however, both tion;

Fig. 2 is a fragmentary, sectional view of inner surface of the mold ofFig. l, larged scale the grooves therein;

Fig. 3 is a fragmentary, developed view on an enlarged scale of theinner mold surface of a mold construction in accordance with the presentinvention;

Fig. 4 is a fragmentary, developed view on an enlarged scale of theinner mold surface of another mold constructed in accordance with thepresent invention;

Fig. 5 is a fragmentary, longitudinal sectional View through a mold ofrelatively small size constructed in accordance with the presentinvention; and

ig. 6 is a fragmentary, longitudinal sectional view through a mold ofrelatively large size constructed in accordance with the presentinvention.

a part of the showing on an ennormal thereto and prefer and 50 withthese Patented July 3, 1956 of the invention, the' finer than thegrooves 3. Although in the particular example shown the grooves 4 dividethe area between the grooves 3 into triangles, it is also possible toprovide additional grooves, similar to grooves 4, dividing these areasinto four cornered areas or into haphazard areas. Instead, of a sixcornered honeycomb arrangement as shown in Fig. 3, it is possible to usepatterns having areas formed with a different number of corners, such asfive or eight cornered honeycomb patterns, and it is not essential thatall the sides of the areas formed by the honeycombpattern of grooves bestraight. The grooves 4 cooperate with the grooves 3 to provide an innermold surface capable of holding a powder in a uniformly distributedmanner. The centers of the areas formed by grooves 3 are substantially.equidistant from the corners and sides of these areas so that anon-uniform stress in the inner mold surface is avoided to a greatextent.

In Fig. 4 there is shown on an enlarged scale a developed view of theinner surface of a further embodiment of a mold constructed inaccordance with the present invention. In this embodiment of theinvention, three sets of parallel, equally spaced grooves intersect eachother toform areas 5 in the shape of equilateral triangles, and, as isapparent from Fig. 4, none of the grooves are parallel to thelongitudinal axis 1 of the mold. During operation of a mold constructedin accordance with Fig. 5, thehigh temperature acting on the inner moldsurface will cause the latter to expand as a result of the stressestherein, and during such expansion, the triangular areas 5 willautomatically group themselves to produce honeycombed six corneredpatterns, such as 6, 7 and 8 of Fig. 4, depending upon the particularstresses produced in the mold during operation thereof. These varioushoney comb. patterns Will be best suited for the particular conditionswithin the interior of the mold. It is also possible for the triangularareas 5 to group themselves together to form an irregular honeycombpattern. This particular form of the invention is particularlyadvantageous because it is very simple to form the areas 5 on the innermold surface.

With conventional centrifugal molds, the larger stresses take place inthe cylindrical part of the mold. However, it has been found that themolds constructed in accordance with the present invention, where thegrooves are inclined to the longitudinal axis of the mold and an axisnormal thereto, the cylindrical part of the mold remains undamaged for along period of time, and the first cracks start to appear in those partsof the mold which are located next to the ends of the uniformcylindrical part.

In order to avoid the formation of cracks in these parts of. the moldwhich are subject to relatively high stresses, the constructions ofFigs. 5 and 6 are provided. In these figures there are shown portions oftwo molds having formed therein grooves 9 and 10 of the sameconstruction as was described above in connectionwith Fig. 1. It hasbeen demonstrated by experience that the above-described centrifugalcasting molds of relatively small size, i. e. below 200-250 mm.diameter, tend to form predominantly longitudinally extending cracks inthe highly stressed regions thereof, and the above-described molds ofrelatively large size, i. e. over 250-300 mm. diameter, tend to producepredominantly circumferential cracks in their highly stressed regions.mold, of Fig. 5: represents a mold of a relatively small size and isformed in its region of extremely high stresses with the longitudinalgrooves 11, while the mold of Fig. 6 represents a mold of relativelylarge size and is formed in its. highly stressed region with thecircumferential grooves 12.

Where the grooves on its inner surface of the mold, such as the grooves9 and 10, have a depth of approximately 0.2 mm., experience hasv shownthat it is best to make the grooves 11 or 12 with a depth ofapproximately 0.5 mm. Also, where these grooves, such as grooves9 and10., are located. apart from eachother by a: distance;

The

of l-2 mm, as was described above, experience has shown that it is bestto locate the grooves 11 or the grooves 12 apart from each other, by adistance of from 2 mm. to 10 mm. Thus, where the grooves 9 or thegrooves it are located apart from each other by a distance of 1.5 mm,the grooves 11 or the grooves 12 would be located apart from each otherby a distance of approximately 6 mm.

Centrifugal casting molds of the type described above may have theirinner surfaces formed with the abovedescribed grooves in a number ofdifferent ways. For example, it is possible to turn the grooves into theinner surface of the mold with a machine tool. One of the most preferredways of forming the indentations, on the inner surface of the mold is touse a knurled wheel having on its outer surface sets of ridges whichintersect each other and are inclined to the longitudinal and transverseaxes of the knurled wheel. This knurled wheel is pressed against theinterior surface of the mold, and the mold and knurled Wheel are movedwith respect to each other so that the knurled wheel moves with respectto the mold circumferentially about the inner surface thereof and movesaxially with respect to the same, at the proper rate, so that thedesired indentations are in this Way formed on the interior of the mold.The advantages resulting from this process of forming the grooves on theinterior of the mold are not only in. its simplicity but also in thefact that the material of the mold is compressed by the knurled wheel soas to greatly strengthen the mold.

It will be understood that each of the elements, described above, or twoor more together, may also find a useful application in other types ofcentrifugal molds differing from the types described above.

While the invention has been illustrated and described as embodied incentrifugal molds having on their inner surfaces grooves which areinclined to the longitudinal and transverse axes of the molds, it is notintended. to be limited to the details shown, since variousmodifications and structural changes may be made Wtihout departing inany way from the spirit of the present invention.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can by applying current knowledgereadily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharacteristics of the generic or specific aspects of this invention.and, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. An elongated, tubular, centrifugal casting mold having an. innersurface formed with a plurality of elongated, intersecting grooveswhichare inclined to the longitudinal axis of the mold and an axisnormal to the longitudinal axis and make an angle of between 40 and 50with at least one of said axes.

2. An elongated, tubular, centrifugal casting mold having an innersurface formedwith a pluality of elongated, intersecting grooves whichare inclined to the longitudinal axis of, the mold and an axis normal tothe longitudinal axis and make an angle of between 40" and 50"- withboth of said axes.

3. An elongated, tubular, centrifugal casting mold having an innersurface formed with a plurality ofgrooves arranged in a honeycombpattern and all being inclined to the longitudinal axis of the mold.

4. An elongated, tubular, centrifugal casting mold having an innersurface formed with a plurality of grooves arranged in a inclined to thelongitudinal axis of the mold, said inner surface. having the portionsthereof located between said grooves formed with additional groovesfiner than said' honeycomb pattern and all being first-mentioned groovesand dividing said portions into polygonal areas.

5. An elongated, tubular, centrifugal casting mold formed on its innersurface with three sets of parallel grooves, said sets intersecting eachother and all pairs of adjacent grooves of said three sets of groovesbeing located apart from each other by equal distances, and said groovesforming between themselves areas on the inner surface of the mold havingthe shape of equilateral triangles, all of said grooves being inclinedto the longitudinal axis of the mold and an axis normal to saidlongitudinal axis.

6. A centrifugal casting mold as defined in claim 5 and wherein all ofsaid grooves are of the same depth.

7. A centrifugal casting mold as defined in claim 5 and wherein eachpair of adjacent grooves of said three sets of grooves are located apartfrom each other by a distance of approximately 1.5 mm.

8. An elongated, tubular, centrifugal casting mold having a diameter ofless than 250 mm., being formed on its inner surface with intersectingsets of grooves all of which are inclined to the longitudinal and axisof said mold and an axis normal to said longitudinal axis, and beingformed at parts thereof which are subjected to relatively great stresseswith an additional set of grooves substantially parallel to thelongitudinal axis of said mold.

9. An elongated, tubular, centrifugal casting mold having a diameter ofmore than 250 mm., being formed on its inner surface with intersectingsets of grooves all of which are inclined to the longitudinal axis ofsaid mold and an axis normal to said longitudinal axis, and being formedat parts thereof which are subjected to relatively great stresses withan additional set of circumferential grooves located about thelongitudinal axis of said mold.

10. A centrifugal casting mold as defined in claim 8 and wherein saidadditional set of grooves are approximately 0.5 mm. deeper than saidintersecting sets of grooves and located apart from each other by adistance of from 2 to 10 mm.

11. A centrifugal casting mold as defined in claim 9 and wherein saidadditional set of grooves are approximately 0.5 mm. deeper than saidintersecting sets of grooves and located apart from each other by adistance of from 2 to 10 mm.

References Cited in the file of this patent UNITED STATES PATENTS OTHERREFERENCES Catalog Reed Knurls, by Reed Small Tool Works, Worcester,Mass., Catalog No. 62, Jan. 1, 1944, pages 3 and 9, item 20 (AM, AF orWM).

1. AN ELONGATED, TUBULAR, CENTRIFUGAL CASTING MOLD HAVING AN INNERSURFACE FORMED WITH A PLURALITY OF ELONGATED, INTERSECTING GROOVES WHICHARE INCLINED TO THE LONGITUDINAL AXIS OF THE MOLD AND AN AXIS NORMAL TOTHE LONGITUDINAL AXIS AND MAKE AN ANGLE OF BETWEEN 40* AND 50* WITH ATLEAST ONE OF SAID AXES.